Development of a safe, effective and affordable vaccine for HIV-1 is potentially the most efficient means of controlling HIV-1 infection worldwide. However, the genetic and biological variability of HIV-1 represents significant obstacles for vaccine development. Recent evidence indicates that CTLs may play a role in clearing viremia during primary infection and maintaining a disease-free state in HIV-1-infected patients. Thus, efforts to develop an HIV vaccine should focus on eliciting a broad cross-reactive CTL response as one major component. One promising approach to generating an effective CTL response in vivo is through the use of DNA vaccination. Current efforts using HIV-1 env and gag/pol DNA constructs as immunogens suggest that additional vaccine components are needed to confer broad protection. Therefore, a putative HIV-1 vaccine might benefit by inclusion of additional immunogenic targets. In addition to the structural and enzymatic proteins, HIV-1 also contains regulatory and accessory genes. These genes are highly conserved in vivo and may provide additional targets for CTL responses. We hypothesize that such targets could induce a broad virus-specific CTL response that could help to limit viral escape and confer protection against viral challenge. To use the accessory genes as part of a multicomponent vaccine, we have engineered a novel construct that expresses HIV-1 accessory genes vif, vpu, and nef under the control of a single promoter. To test the "proof of concept" we propose the following aims: (1) We will immunize human HLA-A2 transgenic mouse and evaluate the cellular immune responses using HIV-1 infected human targets; (2) we will use a non-human primate model to test the ability of this vaccine construct to confer protection either alone or in combination with env and gag/pol vaccine constructs. We hypothesize that cell-mediated responses induced by the accessory genes may include broader recognition of divergent HIV-1 clades and should be useful in both prophylactic as well as therapeutic vaccination schemes against HIV-1.